As we know, Peirce's writings have inspired many new theories and discoveries for well over a century.  But we must always distinguish his exact words from anybody else's interpretations and extensions.

For interpretants, I believe that an article Jay Zeman wrote in 1977 is still one of the best:  "Peirce's Theory of Signs", which has 70 occurrences of the word 'interpretant', 

Since CP is the only source he cites, he avoids the dubious late extensions that Short and others have criticized.  It provides a good foundation for readers to distinguish Peirce's earlier, more limited definitions from later extensions that Peirce himself failed to define clearly and precisely.

I have a copy of that article on my website, and I checked Google to find a more official site.  But the search pointed back to my own website:  https://www.jfsowa.com/ikl/Zeman77.pdf 

After Zeman died, I downloaded  a complete copy of his entire website.  I believe that it should be preserved somewhere more official.  If anybody knows of a more official place to store it, I would be happy to give them access to the whole thing.

John